York Heat Pump: Yorkguard IV & Yorkguard V

Re: Flashing Code 2 (Heating)

Code 2 = High Discharge Pressure

If the Hi Pressure circuit input on the Yorkguard opens, the module will go into a Code 2 lockout and disable compressor operation.

CHECKOUT:

1. Check Operation

• Make sure the thermostat is set correctly and calling for Heat.
• Check to see if sufficient air flow is coming from the supply registers.
  • No Airflow → Step 2. Check Blower Motor
  • Airflow → Step 3. Check Refrigerant Pressures

2. Check Blower Motor & Capacitor

• Check Capacitor
  • Turn off all power to the unit.
    • Use a multi-meter to confirm that voltage is not present.
  • Remove capacitor wires (short before touching)
  • Move Multi-Meter leads to COM and MFD.
  • Set Meter to 200 MFD.
  • Place one lead on each side of the capacitor. 
  • Confirm MFD reading with capacitor rating.
    • Less than 80% of rating = Bad Capacitor
  • SWITCH METER LEADS BACK TO COM AND V BEFORE PROCEEDING!
• Check Blower Motor
  • Re-apply power to the air handler or furnace.
  • Set the thermostat to call for heat.
  • Check for 24VAC from "G" to "C" on the low voltage wiring.
    • No Power = No call for fan from the thermostat.
  • Check for 230V across blower motor "COM" and the Speed wire.
    • Power but No Motor Operation = Bad Blower Motor
    • No Power = Bad Fan Control

3. Check Refrigerant Pressures

• Hook-up refrigerant gauges to the pressure ports on the unit.
  • Blue ⇔ "True Suction" (NOT THE SUCTION LINE) Low Pressure Port
  • Red ⇔ High Pressure (either refrigerant line)
• If the heat pump is in lockout (still flashing a code), reset by removing and reconnecting "Y", or cycle power to the air handler.
  • Wait for 5 min. Anti-Short-Cycle Delay to expire, or bypass timer by jumping the Test pins (Yorkguard V only).
• Monitor pressures as the system operates.

• Pressure switch trips immediately or while the discharge pressure is in a normal operating range = Bad Pressure Switch.

• High Pressure Issues
  • Place an insulated temperature probe on the liquid line between the evaporator coil & O/D expansion valve.
  • Allow the unit to run for at least 10 minutes.
  • Monitor pressures and temperature as the system operates.
    • If pressure exceeds Normal Range and kicks-off on Hi Pressure safety in the first 5 minutes = Refrigerant Overcharge or No Indoor Blower
  • Check Sub-Cooling (only if there is an expansion valve in the o/d unit)
    • Record "Saturation Temperature" from the discharge pressure gauge.
    • Subtract the Actual liquid line temperature reading.
      • Saturation Temp - Liquid Line Temp = Sub-Cooling
      • Sub-Cooling > 13 deg. + High Discharge + High Suction = Overcharged
      • Sub-Cooling > 13 deg. + High Discharge + Low Suction = Bad Expansion Valve
      • Sub-Cooling < 2 deg. + High Discharge = Low Indoor Heat Transfer → Step 4. Check Air Temperature Rise

4. Check Air Temperature Rise

• With the auxiliary heaters disconnected (remove "W1" and "W2" form the air handler terminal block):
• Check the Return Air Temperature near the unit or in the filter compartment.
• Check the Supply Air Temperature.
• Normal Temperature Rise = 15-20 deg.
  • High Temperature Rise = Low Airflow
    • Remove the air filter and re-check the Temperature Rise.
      • Returns to Normal = Clogged Air Filter
      • Still High ⇒ Check for Dirty Indoor Coil
• RE-HOOK "W1" AND "W2" WIRES ON THE AIR HANDLER!